CODEWITHSUNDEEP
pythonsortingdictionary
warun26
warun26

Reputation: 453

Sorting python dictionary

I have a dictionary where the values are floating point numbers. I am trying to sort the dictionary in decreasing order of values and I am trying to break ties by sorting the keys in ascending order.

I implemented the following code to achieve this: 

for key, value in sorted(dictionary.items(), key=lambda x: (-x[1], x[0])):

    print key, value

Some of my values seem out of place.

2315 0.000232471518033

2823 0.000232414850716

3649 0.00023239634392

3695 0.00023239634392

3883 0.00023239634392

3479 0.00023239634392

3562 0.00023239634392

3613 0.00023239634392

As per the above code line starting with 3479 should be printed before the line starting with 3649.

Any ideas on what might be wrong with the way I have sorted the dictionary? Has it got anything to do with the precision of floating point numbers?

Upvotes: 1

Views: 114

Answers (2)

Helios83
Helios83

Reputation: 87

I think you are ordering with respect to the wrong components of the dictionary. You can just do:

for key, value in sorted(dictionary.items(), key=lambda x: (x[0]):
print key, value

if you want to order per key, and 

for key, value in sorted(dictionary.items(), key=lambda x: (-x[1]):
print key, value

if you want to order per value.

Upvotes: 0

Ignacio Vazquez-Abrams
Ignacio Vazquez-Abrams

Reputation: 799450

Has it got anything to do with the precision of floating point numbers?

Yes.

>>> 0.0002323963439201
0.0002323963439201
>>> print 0.0002323963439201
0.00023239634392

Upvotes: 7

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